1. Field of the Invention
The present invention relates to an information recording method for recording information by alternately and repeatedly carrying out a data recording operation and a verifying operation in the control of an information recording and reproducing apparatus employing a disk shaped information recording medium having a spiral track.
2. Description of the Prior Art
In an optical disk, normally an optically detectable guide track such as guide groove is provided to render the track density high. On the recording layer on the guide track a laser light concentrated to about 1 .mu.m is irradiated to induce an optically detectable change such as boring or phase change to record information. The recording pitch or track pitch is very small, about 1 .mu.m, so that, depending on the manufacturing process or the operation environment of the optical disk, various kinds of defects, dust, flaws, etc. are formed giving rise to dropout of the reproduced signal. Accordingly, the error rate before error correction of the optical disk is about 10.sup.-4 to 10.sup.-6, which is extremely large in comparison with that of the magnetic disk being 10.sup.-9 to 10.sup.-12, and a number of defective sectors are generated on the optical disk.
Accordingly, in an optical disk unit, in order to assure reliability of data, a verifying operation is required to be performed after the data recording operation. In the verifying operation, an error detection is performed against the data read out in a sector unit. When an uncorrectable error has been detected, defect management is necessitated. If a data necessary for defect management recording is stored in an optical disk unit, the optical disk unit is allowed to perform defect management efficiently.
Practically, however, the memory capacity contained by an optical disk unit is limited, and sometimes all the data cannot be stored. In such a case, the data to be recorded is divided into plural sections, and the recording operation and the verifying operation on the divided data re carried out alternately and repeatedly.
Hereinafter, the data recording operation and the verifying operation to be carried out alternately and repeatedly in the conventional optical disk unit is explained with reference to the drawings.
FIG. 5 is a block diagram showing an ordinary optical disk unit. Between an optical disk drive 51 and a host system 52 there is disposed an optical disk drive controller 58. An optical disk 59 having a spiral track is housed in the optical disk drive 51. The optical disk drive controller 58 is constructed by a memory circuit 53, an interface circuit 54, a data modulation and demodulation circuit 55, an error detection and correction circuit 56, and a microcontroller 57. In the memory circuit 53, the control data necessitated by the microcontroller 57 and the recording and reproducing data are stored. The interface circuit 54 controls the data transfer between the hose system 52 and the optical disk drive controller 58. The data modulation and demodulation circuit 55 performs modulation and demodulation of data. The error detection and correction circuit 56 performs encoding and decoding of the error correction code. The microcontroller 57 controls the interface circuit 54, the data modulation and demodulation circuit 55, and the error detection and correction circuit 56.
FIG. 6 shows a format diagram of the optical disk 59, in which a continuous spiral track starting from track T.sub.0 is equally divided into 18 sectors from S.sub.0 to S.sub.17.
FIG. 7 is a view to illustrate the operation in the conventional optical disk unit, showing the state where the data recording operation and the verifying operation are repeatedly carried out. In FIG. 7, a latency corresponding to 1 sector is represented by .tau..sub..tau.. The term "latency" denotes a rotational delay of a disk drive, i.e., the time needed for data to rotate under the recording and reproducing head once the head is in position over the appropriate track.
Hereinafter, the 40-sector data writing operation for alternately and repeatedly performing the data recording operation and the verifying operation in the processing unit of the 1 track data mount is explained with reference to FIG. 7. Here, it is assumed that, of the seek operation to the starting sector for performing a verifying operation after the data recording operation, the time required for the inter-track jump operation corresponds to the 4-sector latency. Also, it is assumed that a latency corresponding to 3 sectors in total is required for performing the post-process of the verifying operation and the pre-processes for the next data recording operation.
First, the processing 701 or the data recording operation for 18 sectors from sector S.sub.0 of track T.sub.1 to sector S.sub.17 of track T.sub.1 is carried out. Then, in the processing 702, a seek operation of the data to be verified to the heat track T.sub.1 sector S.sub.0 is carried out. For the purpose of this seek operation, a latency corresponding to at least 4 sectors for the inter-track jump operation is required, and for the seek operation in the processing 702, a latency corresponding to 1 track is required.
Next, in the processing 703, the verifying operation for 18 sectors from the sector S.sub.0 of the track T.sub.1 to the sector S.sub.17 of the track T.sub.1 are carried out. The subsequent second time data recording operation is performed from the track T.sub.2 sector S.sub.0. However, as a latency corresponding to 3 sectors in total is required to perform the post-process of the verifying operation and the pre-processes for the next data recording operation, in the processing 704, a latency of 15 sectors is performed for the seek operation to the track T.sub.2 sector S.sub.0.
Thereafter, the processing 705 for an 18 sector data recording operation, the processing 706 or latency for the seek operation, the processing 707 for the 18 sector data verifying operation, and again the processing 708 or latency for the seek operation, the processing 709 for the 4 sector data recording operation, the processing 710 or latency for the seek operation, and finally the processing 711 for a 4 sector data verifying operation are similarly repeated to complete the 40 sector data recording operation.
FIG. 8 is a time chart for illustrating the detailed processing in the conventional optical disk unit. Using FIG. 8, the operation from the processing 701 to the processing 704 is described in more detail.
The processing 701 for an 18 sector data recording operation is carried out as follows: The data transferred sector by sector from the host system 52 are passed through the interface circuit 54 and stored in the memory circuit 53. Further, the error detection and correction circuit 56 adds an error correction code to the data in the memory circuit 53 in the encoding operation in the unit of 1 sector. Further, the encoded data is modulated in the data modulation and demodulation circuit 55 and sent to the optical disk drive 51, and written in the sector S.sub.0 of the track T.sub.1 on the optical disk 59. The data modulation and writing operations, the encoding operation in the next sector, and further the transfer of the data from the host system 52 in the next sector are performed in parallel with one another repeatedly. Further, at the time when the writing of the data of 18 sectors up to the sector S.sub.17 of the track T.sub.1 has been completed, the processing 701 or the data recording operation for the first 1 track is terminated.
Next, the processing 702 for a seek operation is carried out. The optical disk drive controller 58 sends a seek operation command to the optical disk drive 51 so as to perform the processing 703 or verifying operation from the sector S.sub.0 of the track T.sub.1, since the track structure of the optical disk 59 is spiral. In the optical disk drive 51, the processing 702 or seek operation of the sector S.sub.0 to the track T.sub.1 is performed. However, at the time when the jump operation between the tracks for the seek operation has completed, the unillustrated recording and reproducing head of the optical disk drive 51 is not ready on the sector S.sub.0. For this reason, for the seek operation of the sector S.sub.0 to the track T.sub.1 in the processing 702, a latency corresponding to one cycle rotation of the optical disk 59 is required.
Then, the processing 703 or verifying operation of the data of 18 sectors is performed. On completion of the seek operation of the processing 702, the data modulation and demodulation circuit 55 demodulates the data read out in the unit of 1 sector from the sector S.sub.0 of the track T.sub.1. Further, the error detection and correction circuit 56 checks for the existence of an uncorrectable error while decoding the demodulated data. The data decoding operation and the demodulation operation to the next sector are concurrently performed. If no error is detected, a verifying operation for the 18 sectors up to the sector S.sub.17 of the track T.sub.1 is performed. If an error is detected during the verifying operation, the processing 703 is discontinued, and a processing to substitute the sector in which the error has been detected for other sector is performed.
Thereafter, the processing 704 or a latency for the seek operation is performed. The post-process in the verifying operation of processing 703, or the decoding operation of the sector S.sub.17 of the track T.sub.1, is completed when the head is located on the sector S.sub.0 of the track T.sub.2. However, in order to perform a data recording operation from the sector S.sub.0 of the track T.sub.2, when the head is located on the sector S.sub.16 of the track T.sub.1, data transfer of the sector S.sub.0 of the track T.sub.2 must be performed as pre-processes of the data recording operation. Accordingly, for recording the data from the sector S.sub.0 of the track T.sub.0 in the processing 705, a latency corresponding to 15 sectors is required for the seek operation of the processing 704.
However, in the abovementioned conventional embodiment, because of the seek operation necessitated for performing a verifying operation after the data recording operation, there arises a latency corresponding to one cycle rotation of a disk with the addition of a latency to the time required for the inter-track jump operation. Also, in the conventional embodiment as described above, because of the necessity to perform a post-process of the verifying operation and pre-processes of the data recording operation, it is not possible to perform the data recording operation from the recording sector immediately following the termination of the verifying operation, so that there arises a latency corresponding to 15 sectors during the time from the verifying operation to the succeeding data recording operation.
As described above, there arises a latency between the data recording operation and the verifying operation, resulting in an elongation of the data processing time.